The Open3DPrinted Camera is an actual, working SLR, and with some help from a custom mount ring, it can work with any SLR lens you might have. The resulting photos aren't bad, either.

According to Bozardeux's Instructables project, the body takes a bit less than 15 hours to print, and requires about an hour of your time to assemble. And you can make your own—Bozardeux posted the model files to Thingiverse, and says that you can print it on a "recent RepRap-like ABS 3D-printer without using support material."

Also, since Bozardeux released the build under a Creative Commons Attribution Share Alike (CC BY-SA) license, you can make your own changes to the design, provided you release it under the same license. Looks like fun. Visit the project page on Instructables and find out how you can make your own.